Pollinator behaviour and morphology to understand pollination niche partitioning in co‐occurring closely related plant species

Pollinator foraging behaviour shapes a plant's pollination niche, with direct consequences for natural selection and plant evolution. However, the extent to which individual‐ and species‐level pollinator behaviour, and the drivers of such behaviour, actually influence pollination niche partitioning remains poorly understood.

We examined the pollination niche of two Glandularia species and their rare hybrid in both a natural community and an experimental setting, controlling flower abundance. We assessed the variation in insect pollinator foraging behaviour (i.e., floral preference, specificity and constancy), and traits that may influence these foraging choices, as potential drivers of pollination niche partitioning.

We found an effective partition in the pollinator assemblage according to the Glandularia phenotype. Although the pollination niche varied between the two flower display contexts, pollinator choices were not solely explained by differences in the flower display.

Plant–pollinator interaction preferences increased with trait matching and floral constancy was stronger and more stable among specialist pollinators than among generalist pollinators, indicating greater consistency in the foraging behaviour of specialised pollinators.

Our findings enhance our understanding of the mechanisms linking pollinator behaviour with the floral traits that shape it, providing key evidence of how these interactions influence plant evolutionary dynamics.